The present invention relates generally to electronic music apparatus which generate tones in response to performance operation by human players. More particularly, the present invention relates to an improved electronic music apparatus which is suitable for use in, for example, music therapy etc., and which, in an application where the electronic music apparatus is connected with one or more other electronic music apparatus of a similar construction, allows the respective users of the music apparatus to execute desired performance operation and simultaneously listen to tones generated in response to their performance operation.
There have been known electronic music apparatus, for example, from Japanese Patent Application Laid-open Publication No. HEI-10-031482 which corresponds to the U.S. Pat. No. 5,856,628. The known electronic music apparatus each include a performance operator unit, a tone generator for generating tone signals in response to performance operation, by the user or human operator, on the performance operator unit, external input section, external output section, speaker output section, and mixer circuitry. The tone signals generated by the tone generator and externally received via the external input section are mixed via the mixer circuitry, and the resultant mixed tone signals are supplied not only to the speaker output section but also to an external device located outside the electronic music apparatus in question.
Recently, music therapy (i.e., treatment of a physical problem or illness based on music) has been employed extensively in medical facilities etc. Some of the music therapy utilizes musical instrument performances, where rehabilitation and/or the like of a patient is carried out by the patient and healer (or care taker, such as a facilitator) individually performing musical instruments to communicate with each other via the instrument performances. As one example of the musical instrument, an electronic music apparatus may be suitably used for music therapy in medical facilities, which is small in size for convenient portability and has a headphone set etc. capable of effectively preventing leakage therethrough of sounds to other persons than the user of the music apparatus due to limitations on its installed position, necessity to minimize noise sounds and so on. In a case where such small-size electronic music apparatus with the respective headphone sets are to be used by a plurality of users, it suffices to connect together these electronic music apparatus via connecting cables in such a manner that each of the users can listen, through the headphone set, to tones performed by that user and by the user of the other music apparatus; namely, the users of the connected music apparatus can listen to each other's performance tones through their respective headphone sets. For example, if the external output section of the first electronic music apparatus is connected to the external input section of the second electronic music apparatus and the external output section of the second electronic music apparatus is connected to the external input section of the first electronic music apparatus, the users of the first and second electronic music apparatus can listen, through their respective headphone sets, to each other's performance tones (i.e., tones performed by the users of the two music apparatus).
However, the external input section of the conventional electronic music apparatus is merely designed to receive tones (audio signals) reproduced via an external audio device or the like, such as a compact disk player, but never designed for use in an application as mentioned above where the external output sections and input sections of a plurality of the electronic music apparatus are connected with each other so that an output from one of the music apparatus is delivered to the other music apparatus. Therefore, it has been very difficult to connect together a plurality of the conventional electronic music apparatus for use in music therapy. Namely, in the case where a plurality of the conventional electronic music apparatus are connected together, each performance tone of the first electronic music apparatus is returned, via the second electronic music apparatus, to the external input section of the first electronic music apparatus, i.e. a closed loop is formed between the first and second electronic music apparatus, which would result in unwanted howls in the outputs from the headphone set; thus, it has been difficult to use the conventional electronic music apparatus in music therapy. Alternatively, arrangements may be made such that each output from the first electronic music apparatus is passed to the second electronic music apparatus and each output from the second electronic music apparatus is divided into two outputs so that the respective users of the first and second electronic music apparatus can listen to the same tones simultaneously. In such a case, a relatively long connecting cable has to be provided to extend from the second electronic music apparatus; however, in medical facilities where music therapy is carried out primarily, laying such a long connecting cable is rather improper in that it may induce troubles and accidents. Namely, because no electronic music apparatus has ever been developed which allows the respective users of that music apparatus and other electronic music apparatus, connected thereto, to simultaneously perform desired tones and simultaneously listen to each other's performances, it is still not possible to appropriately use electronic music apparatus for music therapy etc., which would result in not a few inconveniences.